Department of Radiobiology/Molecular Epidemiology

There is numerous epidemiological data on the
effects of radiation exposure on disease incidence and death in
humans. However, the biological mechanisms underlying the observed
effects of atomic-bomb radiation on the development of human diseases,
especially cancer, are unknown.The Department
of Radiobiology/Molecular Epidemiology uses molecular oncological and immunological approaches with epidemiological
study design, to investigate radiation effects on health and to clarify
the etiology of diseases among atomic-bomb survivors and their children,
in terms of host-environment interaction.

Molecular Oncology
Studies: Most researchers believe the process of cancer development
involves multiple steps. For a normal cell to become malignant,
mutations and alterations of selected genes must accumulate in the
cell, often resulting in disfunction of regulatory systems responsible
for the tightly controlled cell growth and death. Ionizing radiation
is known to damage DNA, e.g., gene mutations and epigenetic changes.
Presumably, atomic-bomb radiation damaged some of the important
genes involved in cancer development.

Immunology Studies: The immune system
protects the body from the intrusion of alien substances, such as
bacteria and parasites, and in some cases from the continued proliferation
of malignant cells or even from constantly-generating malignant
cells (immunosurveillance against cancer). Host immunological response,
specifically inflammatory response, is thought to be a key mechanism
in development of various lifestyle-associated diseases such as
diabetes, coronary heart disease, and several cancers. Through repeated
division, a pool of blood stem cells produces cells that, in turn,
differentiate into the functionally and phenotypically heterogeneous
cell subpopulations that make up the immune system. These subpopulations
closely interact with and regulate one another to effectively eliminate
intruding substances.

Immunogenome Studies: The human genome,
the complete set of genetic information in people's DNA, differs
among individuals, and this is in part responsible for individual
differences in biological predispositions such as susceptibility
to environmental chemicals, radiation exposure, and development
of lifestyle-associated diseases. Our Immunogenome Study
investigates genetic polymorphisms responsible for inter-individual
differences in susceptibility to radiation effects and also the
development of lifestyle-associated diseases such as cancer and
diabetes mellitus, aiming at personalized prevention of radiation-associated
diseases.

Research Scientists
and their Research Interests

Yoichiro Kusunoki, PhD, Department Chief

Radiation exposure and immunosenescence

Molecular epidemiology on immune-related diseases

Tomonori Hayashi, PhD, Assistant Department Chief

Immunosenescence in the radiation exposed

Genetic susceptibility to immune-related diseases

Homeostasis and intercellular communication

Kei Nakachi, PhD, RERF Consultant and Project Principal Scientist

Studies of immunosenescence and other late effects of acute ionizing radiation
exposure in A-bomb survivors